Washington University in St. Louis
Campus Box 1137
One Brookings Drive
St. Louis, MO 63130-4899
This lab uses the spherical green alga Volvox carteri, which exhibits a complete division of labor between many small, mortal somatic cells, and a few large, immortal germ cells, as a model system to analyze how a program for cellular differentiation may be encoded in a genome, and how such a program may evolve. Mendelian and molecular studies indicate that three kinds of genes are involved in programming this germ-soma dichotomy: first gls genes act to cause embryonic cells to divide asymmetrically, producing large and small cells; then the lag genes act in large cells to repress somatic development, while the regA gene acts in the small cells to repress reproductive development. The evolution of these genes is now being studied.
Photo caption: Juvenile spheroids of Volvox carteri hatching out of a parental spheroid. Each juvenile contains a surface monolayer of small somatic cells and several large asexual reproductive cells called gonidia.
Kirk, M.M., Stark, K., Miller, S.M., Muller, W., Taillon, B.E., Gruber, H., Schmitt, R., Kirk, D.L. (1999) RegA, a Volvox gene that plays a central role in germ-soma differentiation, encodes a novel regulatory protein. Development 126: 639-647.
Meissner, M., Stark, K., Cresnar, B., Kirk, D.L., Schmitt, R. (1999) Volvox germline-specific genes that are putative targets of RegA repression encode chloroplast proteins. Curr. Genet. 36: 363-370.
Miller, S.M., Kirk, D.L. (1999) GlsA, a Volvox gene required for asymmetric division and germ cell specification, encodes a chaperone-like protein. Development 126: 649-658.
Stark, K., Kirk, D.L., Schmitt, R. (2001) Two enhancers and one silencer located in the introns of regA control germ-soma differentiation in Volvox carteri. Genes Dev. 15: 1449-1460.